Amicrophoneis an
acoustical to mechanical to electrical transducer. There are
four popular types of microphones: dynamic,
ribbon, condenser, and piezoelectric.

Dynamic Mic
A dynamic microphone
manages the
acoustical-to-mechanical step via a light diaphragm that mechanically shadows-and-responds to the
rarefactions and compressions of sound.
The
mechanical-to-electrical step attaches a coil of wire surrounded by a
magnet to a light diaphragm. Sound waves modulate the diaphram-coil
in the magnetic field which produces a small voltage. This voltage is an analog of the
original sound that can be amplified or recorded.

Ribbon Mic
A ribbon mic places
a thin
aluminum film/metal element between magnetic poles rather than a dynamic mic diaphragm. As
the dynamic mic, the modulating film and its magnetic field produces a small voltage. As the dynamic mic, that
voltage is an analog of the original sound.

Condenser Mic
The
acoustic-to-mechanical
diaphragm of a condenser mic is essentially one plate
of an
electric-static-charged capacitor. The
mechanical-to-electrical
stage places this diaphragm plate near
a battery supplied
electro-magnet backplate.
Changes in
the modulating distance
between the diaphragm and the charged backplate creates
an instantaneous voltage. That voltage is
an analog of
the original sound.

Piezoelectric Mic
A piezoelectric
mic uses an allmost all-in-one
acoustic-to-mechanical-to-electrical transducer. This
transducer uses a natural
crystal that produces voltage when sound pressure is applied by a modulating diaphram. Piezoelectric
microphones
literally squeeze voltage from the crystal.
Its voltage is an analog of the original sound.

TheSpeaker

A speaker is an inverted microphone. It's an electrical-to-mechanical-to-acoustic transducer.
As the microphone there are four popular types of speakers:
dynamic, ribbon, electrostatic, and piezoelectric.

Dynamic Loudspeaker
The dynamic
loudspeaker is the most prominent type of loudspeaker. The
output
from an amplifier is connected to a coiled wire (creating an
electromagnet)
surrounded by a fixed magnet. Continuous modulating
changing electromagnetic polarity of the amplifier creates a
push/pull effect. The electro-magnet-coil is attached to
a speaker cone.
The modulating voltage from the amplifier modulates the
coiled-cone-assembly which in turn reproduces the original
sound from a
microphone or a recording.

Ribbon Loudspeaker
A ribbon loudspeaker is the
reversal of a
ribbon mic. The electrical-to-mechanical mechanism is
comprised
of thin conductive wires attached to a thin ribbon of
Mylar
film placed between vertical arrays of magnet strips.
An amplifier modulates the Mylar
sheet which reproduces an
analog of the original sound.

Electrostatic Loudspeaker
As the condenser mic
an electrostatic speaker is essentially a large flat capacitor.Similar to the condenser mic, a power supply creates an electro-static charged field. The electric-to-mechanical diaphragm is a graphite coated mylar film placed
between charged corrugated grid stators. An amplifiers
modulates the diaphragm which in turn
reproduces the original sound.

Piezoelectric
Speaker
I did not refer to this
speaker as a loudspeaker.
This type of speaker is limited to the reproduction of high
frequency sound in a high fidelity system --- it's a tweeter. This
'tweeter' is the reverse of a piezoelectric microphone element.
In this case an amplifier's voltage is applied to the
crystal.
The modulating pressure/voltage squeezes the piezoelectric
crystal, which modulates its surface and reproduces the original high frequency sound.